“Because it is not known whether the Affordable Care Act will remain, in whole or in part, it would be imprudent for New Jersey to create an exchange at this moment in time before critical threshold issues are decided with finality by the Court,” Christie said.

The exchange legislation, primarily sponsored by Democrats, passed the New Jersey General Assembly in March, shortly before the Supreme Court began its hearings on the law's constitutionality, according to NJToday.

Christie also expressed concerns about the bill's expansion of Medicaid (up to 200 percent of the federal poverty level, from 133 percent); its procedure for determining which plans can be sold on the exchange; and the make-up of the exchange's governing board in his veto, the news service reports.

Last spring, New Mexico Gov. Susana Martinez also vetoed exchange legislation, according to the Santa Fe New Mexican. Alabama Gov. Robert Bentley said last week that he would veto a bill working through that state's legislature, according to WSFA.

States must demonstrate to the U.S. Department of Health and Human Services by January 2013 that they can operate an exchange or a federal-run exchange may be established. According to the National Conference of State Legislatures, 18 states currently have exchange legislation pending, and 11 have already enacted such legislation.